Commit 5a66847e authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

fs: Convert unnamed_dev_ida to new API 



The new API is much easier for this user.  Also add kerneldoc for
get_anon_bdev().

Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
parent 3aed4bc1

fs/super.c

+24 −43
Original line number Diff line number Diff line
@@ -978,58 +978,42 @@ void emergency_thaw_all(void) 
	}

}



/*

 * Unnamed block devices are dummy devices used by virtual

 * filesystems which don't use real block-devices.  -- jrs

 */



static DEFINE_IDA(unnamed_dev_ida);

static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */

/* Many userspace utilities consider an FSID of 0 invalid.

 * Always return at least 1 from get_anon_bdev.

 */

static int unnamed_dev_start = 1;



/**

 * get_anon_bdev - Allocate a block device for filesystems which don't have one.

 * @p: Pointer to a dev_t.

 *

 * Filesystems which don't use real block devices can call this function

 * to allocate a virtual block device.

 *

 * Context: Any context.  Frequently called while holding sb_lock.

 * Return: 0 on success, -EMFILE if there are no anonymous bdevs left

 * or -ENOMEM if memory allocation failed.

 */

int get_anon_bdev(dev_t *p)

{

	int dev;

	int error;



 retry:

	if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)

		return -ENOMEM;

	spin_lock(&unnamed_dev_lock);

	error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);

	if (!error)

		unnamed_dev_start = dev + 1;

	spin_unlock(&unnamed_dev_lock);

	if (error == -EAGAIN)

		/* We raced and lost with another CPU. */

		goto retry;

	else if (error)

		return -EAGAIN;



	if (dev >= (1 << MINORBITS)) {

		spin_lock(&unnamed_dev_lock);

		ida_remove(&unnamed_dev_ida, dev);

		if (unnamed_dev_start > dev)

			unnamed_dev_start = dev;

		spin_unlock(&unnamed_dev_lock);

		return -EMFILE;

	}

	*p = MKDEV(0, dev & MINORMASK);

	/*

	 * Many userspace utilities consider an FSID of 0 invalid.

	 * Always return at least 1 from get_anon_bdev.

	 */

	dev = ida_alloc_range(&unnamed_dev_ida, 1, (1 << MINORBITS) - 1,

			GFP_ATOMIC);

	if (dev == -ENOSPC)

		dev = -EMFILE;

	if (dev < 0)

		return dev;



	*p = MKDEV(0, dev);

	return 0;

}

EXPORT_SYMBOL(get_anon_bdev);



void free_anon_bdev(dev_t dev)

{

	int slot = MINOR(dev);

	spin_lock(&unnamed_dev_lock);

	ida_remove(&unnamed_dev_ida, slot);

	if (slot < unnamed_dev_start)

		unnamed_dev_start = slot;

	spin_unlock(&unnamed_dev_lock);

	ida_free(&unnamed_dev_ida, MINOR(dev));

}

EXPORT_SYMBOL(free_anon_bdev);
@@ -1037,7 +1021,6 @@ int set_anon_super(struct super_block *s, void *data) 
{

	return get_anon_bdev(&s->s_dev);

}



EXPORT_SYMBOL(set_anon_super);



void kill_anon_super(struct super_block *sb)
@@ -1046,7 +1029,6 @@ void kill_anon_super(struct super_block *sb) 
	generic_shutdown_super(sb);

	free_anon_bdev(dev);

}



EXPORT_SYMBOL(kill_anon_super);



void kill_litter_super(struct super_block *sb)
@@ -1055,7 +1037,6 @@ void kill_litter_super(struct super_block *sb) 
		d_genocide(sb->s_root);

	kill_anon_super(sb);

}



EXPORT_SYMBOL(kill_litter_super);



static int ns_test_super(struct super_block *sb, void *data)